In recent years, optical computing techniques have been developed for applications in the oil and gas industry. One such technique has involved the determination of the optical density (i.e., absorbance) of downhole fluids—which can inform the operators of a variety of characteristics of the downhole fluid. However, it is very difficult to record a high resolution optical spectrum of downhole fluid in the spectral region of 400 to 1100 nm, mainly due to two reasons: First, the harsh, high temperature, high pressure downhole conditions prevent the downhole use of sophisticated grating-based or Fourier Transform-based instruments capable of providing high resolution spectrums. Second, since the optical density of oil in the visible and short near infrared spectral region is high (highly opaque), high powered light sources and sensitive detectors are needed to resolve the spectra, which increase the downhole power requirements and render the tool less rugged and robust.
To address these issues to date, the oil and gas industry has relied upon the use of narrow band optical filters because of their resilience in the downhole environment. However, these narrow band optical filters can only record very low resolution spectrums (i.e., four or less optical channels across the spectrum). Such low resolution data spectra fail to provide the amount of data needed to make highly accurate measurements of the downhole environment.